Only since 1996 cohabiting unions have been asked about in the microcensus; response to the question is voluntary. For the time before 1996, and in the case of item nonresponse, the Federal Statistical Office proposes a procedure for the estimation of cohabiting unions that will be explained and tested for validity here. A comparison with the question concept reveals that the estimation concept yields reliable results in the case of cohabiting unions of persons of different sex. In the case of same-sex cohabiting unions, the estimate proves to be less valid.
Hence, a procedure for the identification of cohabiting unions of persons of different sex and cohabiting unions of persons of same-sex in the various survey years is proposed. Up to and including the 1995 Microcensus, cohabiting unions are completely estimated; from the 1996 Microcensus onwards, a combination of question- and estimation concept is used. In addition, preliminary descriptive findings on the distribution and development of this form of living together in partnership since the beginning of the 1970s are presented.Lengerer, Andrea (2007): Zur Abgrenzung nichtehelicher Lebensgemeinschaften im Mikrozensus. ZUMA-Methodenbericht 2007/04 [.pdf]